Fluent material handling – with receiver or receiver coacting mea – Processes – With material treatment
Reexamination Certificate
2000-04-18
2002-08-27
Popovics, Robert (Department: 1723)
Fluent material handling, with receiver or receiver coacting mea
Processes
With material treatment
C141S069000, C210S797000, C210S798000, C210S323200, C210S332000, C210S333010, C210S409000, C210S411000, C210S412000
Reexamination Certificate
active
06439273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method for cleaning filter candles of a candle filter using a cleaning fluid which is in-flowing from the filtrate side into the interior of the candle, which cleaning fluid is pressed through the filter candle, in the direction opposite to the filtrate direction, by means of a gaseous medium under an overpressure, from the interior to the exterior, as well as to apparatus for carrying out such method.
2. Background Information:
In a known method of cleaning filter equipment, the filter cake produced at the filter on the side of the un-filtrate of the filter equipment is removed thereby that the interior space at the inlet-side, as well as part of the filtrate space positioned above the inlet-side interior space, when the exit-side is closed, is filled with water from the un-filtrate side, whereby the air positioned above the water is compressed in the filtrate space. Upon filling in of the water and compression of the air in the upper space of the filtrate space, a discharge is opened all of a sudden on the un-filterated side such that the air under pressure causes an intense back-flow of the water present in the filtrate space, through the filter, and thereby the filter cake accumulated on the un-filtrate side of the filter is removed from the filter, and is mixed with the water present in the un-filtrate space, and with this is removed through the drain from the filter equipment.
This method is rather simple but has the decisive disadvantage which is to be seen therein that the filter cake removed from the filter is mixed with such a volume of water which is nearly equal to the total volume of both interior spaces of the filtering equipment. Since this water which includes the filter cake can not be passed to sewage in this condition, subsequently a laborious separation of the sludge from the water is necessary. This is the cause of high equipment costs and not insignificant operating costs.
In a further known method for cleaning filtering equipment with installed filter, a cleaning fluid is brought to an overpressure, in a separate container, and for carrying out the cleaning, is brought, via an inlet conduit, to the removal-side of the filter equipment, and from there is pressed through the filter in the direction opposite to the direction of filtration. For moving the cleaning fluid from the accumulated (or special, separate) container to the filtering equipment, a gaseous medium under overpressure is used.
As cleaning medium, usefully, water is employed and as gaseous medium air is used. For distribution of the cleaning fluid serve, respectively at the removal-side candle end arranged nozzle-shaped constrictions, or at a distance from such constriction in the candle interior arranged impact bodies, with which the in-flowing cleaning fluid is deflected to all sides in the direction of the interior walls of the candles.
In other words, nozzle-shaped constrictions are arranged at that end of a candle which is at the filtrate removal side, for distribution of the cleaning fluid. Alternatively, at a distance away from such constrictions are arranged impact bodies for deflection of cleaning fluid.
This has the disadvantage that the nozzle-shaped constrictions are present for the introduction of the cleaning fluid into the interior of the filter candle, as well as for the air under pressure, such that on termination of a pressure impulse, a post-flow, or, in other words, a trailing or tailing type of flow behavior, of cleaning fluid is not possible.
In German Laid Open Patent Application No. 2 227 821 there is disclosed a method comprising the steps of emptying the portion or compartment receiving liquid to be filtered and replacing the emptied volume or space with a pressurizing gas acting in the direction opposite to the pressure in the filter elements and the compartment or portion receiving filtered liquid.
In German Laid Open Patent Application 195 18 575 A1 there is disclosed an extension element of the filter candle, which element extends into the filtrate compartment. Water under pressure of cleaning air is then forced through the extension element and the filter candles.
U.S. Pat. No. 5,437,788 to S. A. Geibel et al. is concerned with a filter assembly comprising: a housing divided into a first chamber and a second chamber, the second chamber being arranged to contain a backwash liquid; a filter element disposed in the first chamber and having an interior; a conduit disposed in the second chamber and having an interior which communicates with the interior of the filter element and an opening which communicates with the second chamber; a weep hole arranged to drain backwash liquid from the second chamber into the filter element or the conduit, the weep hole being below the opening in the conduit; and a gas feed pipe arranged to introduce pressurized gas into the second chamber to force the backwash liquid through the conduit and into the filter element.
In other words, this invention is concerned in one aspect with cleaning of tubular filter candles or elements of a tubular filter arrangement, in which vertical tubes or cartridges, i.e., candles, are supported by a filtrate-chamber tube sheet in a vertical cylindrical vessel, compare pages 18-92 and 18-93 in Liquid-Solid Operations and Equipment in PERRY'S CHEMICAL ENGINEERS' HANDBOOK, Seventh Edition, Robert H. Perry and Don W. Green, 1997, The McGraw-Hill Companies, Inc., ISBN 0-07-049841-5, incorporated herein by reference.
Also in other words, in filtration is achieved the separation of two phases, particulate form, i.e., solid particles or liquid droplets in suspension, and continuous, i.e., liquid or gas, from a mixture, herein also referred to as un-filtrate or liquid to be filtered, by passing the mixture through a porous medium. This may be cylindrical element filters, often referred to as candle filters, in which cylindrical elements or sleeves are mounted vertically and suspended from a header sheet, which divides the filter vessel into two separate compartments. The advantage of candle filters is that as the cake grows on the tubular elements the filtration area increases and the thickness of a given volume of cake is therefore less than it would be on a flat element, compare Filtration in Volume 10 of KIRK-OTHMER, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Fourth Edition, Jacqueline I. Kroschwitz; editor, 1993, John Wiley & Sons, Inc., ISBN 0-471-52679-9 (v. 10), also incorporate herein by reference.
OBJECT OF THE INVENTION
The object of the invention resides here therein to find an improved solution with which it is possible, despite introduction of the gaseous medium under pressure, that there is achieved, at all times, an automatic post-flow of the cleaning fluid into the candle interior, so that, in a practical manner, constantly an impacting of the interior of the candle with this cleaning fluid can be assured.
In other words, there is established in accordance with one object a substantially automatic and effective flow of the cleaning liquid or fluid, including post-flow or tailing or trailing behavior thereof, so as to provide for enhanced removal of filter cake.
Another object resides therein to ensure that a continuously effective layer or sheet or film of cleaning liquid is provided at the interior surface of filter candles so as to assure a more rapid and improved removal of filter cake adhering to a filter element or candle, using an efficient volume of cleaning liquid.
SUMMARY OF THE INVENTION
The present invention teaches that these objects can be accomplished by a method thereby that the cleaning fluid and the gaseous medium are introduced into the interior of the filter candle through stream paths which are separate from one another.
In other words, a gaseous medium and cleaning fluid are flowed through the candle, but through separate passages, in the direction opposite to the direction of flow of the suspension or liquid which is to be filtered.
Thereby it was found useful in independent config
Kolczyk Markus
Krüger Roland
Kuhnt Rainer
Oechsle Dietmar
KHS Maschinen - und Anlagenbau AG
Nils H. Ljungman & Associates
Popovics Robert
LandOfFree
Method and apparatus for cleaning filter candles in a candle... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for cleaning filter candles in a candle..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for cleaning filter candles in a candle... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2917598